Biomolecules are dynamic, not static, systems. Evidence is accumulating that much of the biological action at the molecular level involves intramolecular motion of the entire system. The long-range goal of our work is to investigate experimentally as many facets of biomolecular dynamics as possible and to develop a corresponding theoretical description and understanding. Dynamics involves temporal and spatial aspects. We explore the temporal aspects with flash photolysis in the time range from ns to ks, the temperature range from 4 to 300 K, and the pressure range from 0.1 to 200 MPa. The process studied is the binding of small ligands to a wide variety of heme proteins. The spatial features are investigated by X-ray diffraction over a wide temperature range.